JP6504336B2 - Piezoelectric element, method of manufacturing the same, and piezoelectric element applied device - Google Patents

Description

  The present invention relates to a piezoelectric element, a method of manufacturing the same, and a piezoelectric element applied device.

  Conventionally, various piezoelectric element application devices have been reported in which piezoelectric elements are used in an electro-mechanical conversion mechanism of a micro electro mechanical system (MEMS) element. In a piezoelectric element applied device, a MEMS actuator, a MEMS sensor or the like is mounted as a MEMS element. For example, in a liquid jet head represented by an ink jet recording head, a part of a pressure generating chamber communicating with a nozzle opening is formed by a diaphragm. At the same time, a piezoelectric element is provided on the diaphragm to constitute a MEMS actuator, and the diaphragm is deformed by applying a voltage to the MEMS actuator to pressurize the ink in the pressure generating chamber, whereby the ink droplet is discharged from the nozzle opening. Let it discharge.

  As a piezoelectric layer forming a piezoelectric element of this type, there is one using lead zirconate titanate (PZT) (see Patent Document 1). In addition to the above, there is a situation where research has been conducted on a piezoelectric layer capable of improving the piezoelectric characteristics due to recent demands for further miniaturization, high density, high performance and the like for MEMS elements.

For example, it is a single crystal (Pb (Mg _1/3 , Nb _2/3) formed of a complex oxide of a perovskite type oxide described by the general formula ABO ₃ and in which lead niobate lead oxide and lead titanate are solid-solved. A piezoelectric layer using O ₃ ) -PbTiO ₃ : PMN-PT) has been proposed (see Patent Document 2). PMN-PT is known to exhibit high electromechanical coupling coefficient, piezoelectric constant and relative permittivity (see Non-patent Document 1), and piezoelectrics are obtained by obtaining a piezoelectric layer using such PMN-PT. Improvement of the characteristics is expected. However, for PMN-PT, Mg having a small atomic number segregates at the interface between the piezoelectric layer and the lower electrode in the firing step which is one of the steps of forming the piezoelectric layer, or diffuses in the lower electrode. It has been pointed out that Mg may reach the diaphragm. When Mg is segregated at the interface between the piezoelectric layer and the lower electrode, a good interface can not be formed, resulting in a decrease in insulation and breakdown voltage, leading to a decrease in reliability. In addition, when Mg reaches the diaphragm, a reaction with the constituent material (for example, Si) of the diaphragm occurs at the interface of the lower electrode and the diaphragm, causing a shape defect etc., which may lead to a decrease in reliability. is there.

  From the viewpoint of preventing such a problem, although the kind of metal to be diffused is different, a titanium oxide layer and a bismuth-containing layer are provided between the first electrode and the diaphragm under the piezoelectric layer containing Bi. Has been proposed (see Patent Document 3). Patent Document 3 describes that a titanium oxide layer and a bismuth-containing layer can be used as a stopper to prevent Bi transmitted through the first electrode from being further diffused to the diaphragm.

JP 2001-223404 A Japanese Patent Application Publication No. 2007-088441 JP, 2011-189586, A

T. Ogawa, Jpn. J. Appl. Phys., 47, 7655-7658 (2008)

However, when the titanium oxide layer described in Patent Document 3 is provided with the Mg stopper layer contained in PMN-PT between the first electrode and the diaphragm, the diffused Mg and titanium oxide react with each other, There is a concern that the adhesion between the electrode and the vibrating plate may be reduced, or a shape defect may occur.
In addition, if the first electrode is configured to suppress the diffusion of Mg, the piezoelectric layer and the first electrode can not form a good interface, resulting in a decrease in insulation and breakdown voltage, which may lead to a decrease in reliability. There is.

  As described above, in the prior art, it is difficult to ensure high reliability by using a material (for example, PMN-PT) useful for improving the piezoelectric characteristics. Such a problem is not limited to the case of using PMN-PT, and similarly exists in the case of a piezoelectric element using a piezoelectric material containing Mg. In addition to the liquid jet head, the above-described problems similarly occur in other piezoelectric element application devices on which MEMS actuators or MEMS sensors and the like using such piezoelectric elements are mounted.

  In view of such circumstances, the present invention has an object to provide a piezoelectric element capable of improving piezoelectric characteristics and securing high reliability, a method of manufacturing the same, and a piezoelectric element applied device.

The aspect of the present invention for solving the above problems is a piezoelectric element in which a first electrode, a piezoelectric layer made of a composite oxide of ABO ₃ type perovskite structure containing Mg, and a second electrode are laminated from the substrate side. The first electrode includes a diffusion suppression layer that suppresses the diffusion of the Mg, and a diffusion layer containing Ir that diffuses the Mg relative to the diffusion suppression layer, and the diffusion suppression layer includes A piezoelectric element is provided closer to the substrate than the diffusion layer, and includes a Mg uneven distribution layer in which the Mg is unevenly distributed on the diffusion suppression layer side of the diffusion layer.
According to this aspect, the piezoelectric characteristics can be improved by configuring the piezoelectric layer with a predetermined composite oxide containing Mg. In addition, since the first electrode is provided with the diffusion suppression layer, and the diffusion suppression layer is provided on the substrate side of the diffusion layer, Mg from the piezoelectric layer passes through the first electrode to reach the substrate. You can prevent Further, since the diffusion suppression layer is provided on the substrate side of the diffusion layer, Mg from the piezoelectric layer is diffused into the diffusion layer to be localized in the first electrode, specifically, in front of the diffusion suppression layer. It is possible to prevent localized distribution of Mg at the interface between the piezoelectric layer and the first electrode. As described above, the piezoelectric characteristics can be improved, and a good interface can be formed between any of the piezoelectric layer and the first electrode, and the first electrode and the diaphragm to ensure high reliability. it can. In addition, Mg is an element generally contained in B site. Here, by containing Ir, the diffusion layer can suitably diffuse Mg from the piezoelectric layer into the diffusion layer. Accordingly, excessive distribution of Mg from the piezoelectric layer to the interface between the piezoelectric layer and the first electrode can be avoided, and higher reliability can be ensured.
Further, when the strength of the Mg is measured by secondary ion mass spectrometry in the direction from the piezoelectric layer side to the substrate side, the maximum strength of Mg in the Mg unevenly distributed layer is the diffusion layer and the diffusion suppression layer. It is preferable that the strength of Mg of the The presence of the Mg unevenly distributed layer supports that the diffusion suppressing effect of the diffusion suppressing layer is high. That is, by having the Mg uneven distribution layer, high reliability can be ensured more reliably.
The piezoelectric layer, Pb in the A site of the ABO ₃ type perovskite structure, Bi, at least one further comprise, B site of the ABO ₃ type perovskite structure is selected from the group consisting of K and Na, the It is preferable to further include at least one selected from the group consisting of Nb, Ti and Fe, which contains Mg. According to this, for example, a composite including tetragonal ceramics in which lead niobate magnesium magnate (Pb (Mg _1/3 , Nb ′ _2/3 ) O ₃ ) and lead titanate (PbTiO ₃ ) are solid-solved. An oxide can be obtained, and the composite oxide can form a piezoelectric layer to further improve the piezoelectric characteristics. Besides this, bismuth titanate magnesium oxide (Bi (Mg, Ti) O ₃ ), bismuth ferrate magnesium oxide (Bi (Fe, Mg) O ₃ ), lead niobate magnesium oxide (Pb (Mg, Nb) O ₃ ) And a complex oxide such as bismuth sodium potassium niobate magnesium oxide ((K, Na, Bi) (Mg, Nb) O ₃ ), etc. It can also improve.
Further, the diffusion suppression layer preferably contains Pt. According to this, it is possible to preferably suppress the diffusion of Mg from the piezoelectric layer. Therefore, Mg from the piezoelectric layer does not easily reach the substrate, and higher reliability can be ensured.
The other aspect of this invention which solves the said subject exists in the piezoelectric element application device characterized by including the piezoelectric element as described in any one of said. According to this aspect, it is possible to provide a piezoelectric element applied device excellent in various characteristics, which is equipped with the above-described piezoelectric element capable of improving the piezoelectric characteristics and securing high reliability.
In still another aspect of the present invention for solving the above-mentioned problems, from the substrate side, a first electrode, a piezoelectric layer made of a composite oxide of ABO ₃ type perovskite structure containing Mg, and a second electrode are laminated. In the method of manufacturing a piezoelectric element, the step of forming the first electrode includes the step of providing a diffusion suppression layer that suppresses the diffusion of the Mg, and the Mg on the diffusion suppression layer compared to the diffusion suppression layer. diffusing, only set a diffusion layer containing Ir, the diffusion suppressing layer side of the diffusion layer, the manufacturing method of the piezoelectric element characterized by including a set Keru step a Mg uneven distribution layer to the Mg uneven distribution It is in. According to this aspect, it is possible to provide the above-described piezoelectric element which can improve the piezoelectric characteristics and can ensure high reliability.
In the aspect related to the present invention for solving the above problems, the first electrode, the piezoelectric layer made of the complex oxide of ABO ₃ type perovskite structure containing Mg, and the second electrode are laminated from the substrate side. The first electrode is provided with a diffusion suppression layer that suppresses the diffusion of the Mg, and a diffusion layer that diffuses the Mg relative to the diffusion suppression layer, and the diffusion suppression layer is A piezoelectric element is provided closer to the substrate than the diffusion layer.
According to this aspect, the piezoelectric characteristics can be improved by configuring the piezoelectric layer with a predetermined composite oxide containing Mg. In addition, since the first electrode is provided with the diffusion suppression layer, and the diffusion suppression layer is provided on the substrate side of the diffusion layer, Mg from the piezoelectric layer passes through the first electrode to reach the substrate. You can prevent Further, since the diffusion suppression layer is provided on the substrate side of the diffusion layer, Mg from the piezoelectric layer is diffused into the diffusion layer to be localized in the first electrode, specifically, in front of the diffusion suppression layer. It is possible to prevent localized distribution of Mg at the interface between the piezoelectric layer and the first electrode. As described above, the piezoelectric characteristics can be improved, and a good interface can be formed between any of the piezoelectric layer and the first electrode, and the first electrode and the diaphragm to ensure high reliability. it can. In addition, Mg is an element generally contained in B site.

  Moreover, it is preferable to equip the said diffusion suppression layer side of the said spreading | diffusion layer with the Mg uneven distribution layer which the said Mg unevenly distributes.

  Further, when the strength of the Mg is measured by secondary ion mass spectrometry in the direction from the piezoelectric layer side to the substrate side, the maximum strength of Mg in the Mg uneven distribution layer is the diffusion layer and the diffusion suppression. Preferably it is greater than the strength of the Mg of the layer. The presence of the Mg unevenly distributed layer supports that the diffusion suppressing effect of the diffusion suppressing layer is high. That is, by having the Mg uneven distribution layer, high reliability can be ensured more reliably.

The diffusion layer preferably contains at least one selected from the group consisting of Ir, LaNiO ₃ and SrRuO ₃ . According to this, Mg from the piezoelectric layer can be suitably diffused in the diffusion layer. Accordingly, excessive distribution of Mg from the piezoelectric layer to the interface between the piezoelectric layer and the first electrode can be avoided, and higher reliability can be ensured.

The piezoelectric layer, Pb in the A site of the ABO ₃ type perovskite structure, Bi, at least one further comprise, B site of the ABO ₃ type perovskite structure is selected from the group consisting of K and Na, the It is preferable to further include at least one selected from the group consisting of Nb, Ti and Fe, which contains Mg. According to this, for example, a composite including tetragonal ceramics in which lead niobate magnesium magnate (Pb (Mg _1/3 , Nb ′ _2/3 ) O ₃ ) and lead titanate (PbTiO ₃ ) are solid-solved. An oxide can be obtained, and the composite oxide can form a piezoelectric layer to further improve the piezoelectric characteristics. Besides this, bismuth titanate magnesium oxide (Bi (Mg, Ti) O ₃ ), bismuth ferrate magnesium oxide (Bi (Fe, Mg) O ₃ ), lead niobate magnesium oxide (Pb (Mg, Nb) O ₃ ) And a complex oxide such as bismuth sodium potassium niobate magnesium oxide ((K, Na, Bi) (Mg, Nb) O ₃ ), etc. It can also improve.

  Moreover, it is preferable that the said diffusion suppression layer contains Pt (platinum). According to this, it is possible to preferably suppress the diffusion of Mg from the piezoelectric layer. Therefore, Mg from the piezoelectric layer does not easily reach the substrate, and higher reliability can be ensured.

The other aspect relevant to this invention which solves the said subject exists in the piezoelectric element application device characterized by including the piezoelectric element as described in any one of said. According to this aspect, it is possible to provide a piezoelectric element applied device excellent in various characteristics, which is equipped with the above-described piezoelectric element capable of improving the piezoelectric characteristics and securing high reliability.

Another aspect related to the present invention for solving the above problems is, from the substrate side, a first electrode, a piezoelectric layer made of a complex oxide of ABO ₃ type perovskite structure containing Mg, and a second electrode In the method of manufacturing a piezoelectric element to be stacked, the step of forming the first electrode includes the step of providing a diffusion suppression layer which suppresses the diffusion of the Mg, and the step of forming the first electrode on the diffusion suppression layer compared to the diffusion suppression layer. Providing a diffusion layer for diffusing the Mg. A method of manufacturing a piezoelectric element, comprising the steps of: According to this aspect, it is possible to provide the above-described piezoelectric element which can improve the piezoelectric characteristics and can ensure high reliability.

FIG. 1 is a perspective view showing a schematic configuration of a recording apparatus according to Embodiment 1. FIG. 2 is an exploded perspective view of the recording head according to the first embodiment. FIGS. 2A and 2B are a plan view and a cross-sectional view of a recording head according to Embodiment 1. FIGS. FIG. 2 is a cross-sectional view for describing a configuration of a first electrode and the like of the recording head according to Embodiment 1. FIG. 2 is a cross-sectional view for describing a configuration of a first electrode and the like of the recording head according to Embodiment 1. FIG. 6 is a view for explaining a manufacturing example of the recording head according to the first embodiment. FIG. 6 is a view for explaining a manufacturing example of the recording head according to the first embodiment. FIG. 6 is a view for explaining a manufacturing example of the recording head according to the first embodiment. FIG. 8 is a measurement result of an X-ray diffraction pattern for the piezoelectric element according to the first embodiment. FIG. 8 is a measurement result of displacement characteristics (piezoelectric characteristics) with respect to piezoelectric elements according to Example 1 and Comparative Example 1. FIG. 7 is a measurement result diagram of secondary ion mass spectrometry on the piezoelectric element according to the first embodiment. FIG. 16 is a measurement result diagram of secondary ion mass spectrometry on the piezoelectric element according to Comparative Example 1;

(Embodiment 1)
FIG. 1 is a perspective view showing an ink jet recording apparatus (liquid ejection apparatus) on which an ink jet recording head (liquid ejection head), which is an example of a piezoelectric element applied device according to a first embodiment of the present invention, is mounted.

  As shown, in the ink jet recording apparatus I, an ink jet recording head unit II (head unit) having a plurality of ink jet recording heads is detachably provided to the cartridges 2A and 2B constituting the ink supply means. . The carriage 3 on which the head unit II is mounted is axially movably provided on the carriage shaft 5 attached to the apparatus main body 4 and, for example, it is assumed that the black ink composition and the color ink composition are respectively ejected There is.

  Then, the driving force of the driving motor 6 is transmitted to the carriage 3 through the plurality of gears and the timing belt 7 (not shown), whereby the carriage 3 on which the head unit II is mounted is moved along the carriage shaft 5. On the other hand, the apparatus main body 4 is provided with a conveyance roller 8 as a conveyance means, and the recording sheet S, which is a recording medium such as paper, is conveyed by the conveyance roller 8. The conveyance means for conveying the recording sheet S is not limited to the conveyance roller but may be a belt, a drum or the like.

  According to the ink jet recording apparatus I, since the ink jet recording head according to the present embodiment is mounted, it is possible to improve the piezoelectric characteristics and hence the ink ejection characteristics. In addition to this, high reliability can be ensured by eliminating the risk of causing a shape defect during film formation or processing and an increase in leak current, which can not be prevented only by the prior art. become able to.

  An example of the ink jet recording head 1 mounted on such an ink jet recording apparatus I will be described with reference to FIGS. FIG. 2 is an exploded perspective view of the ink jet recording head according to the present embodiment, and FIG. 3 (a) is a plan view of the substrate (flow path forming substrate) on the piezoelectric element side, and FIG. FIG. 3 is a cross-sectional view according to the line AA ′ of FIG.

  As illustrated, in the flow path forming substrate 10, the pressure generating chambers 12 are divided by a plurality of partitions 11, and the pressure generating chambers 12 extend in the direction in which the nozzle openings 21 for discharging the ink of the same color are arranged. It is installed side by side. Hereinafter, the direction in which the pressure generating chambers 12 in the flow path forming substrate 10 are arranged in parallel will be referred to as a width direction or a first direction X, and a direction perpendicular to the first direction X to form a substrate plane will be referred to as a second direction Y It is called.

  The ink supply whose opening area is reduced by narrowing one side of the pressure generating chamber 12 in the first direction X on one end side of the pressure generating chamber 12 arranged in parallel to the flow path forming substrate 10 in the second direction Y The passage 13 and the communication passage 14 having substantially the same width as the pressure generation chamber 12 in the first direction X are partitioned by the plurality of partitions 11, and the pressure generation outside the communication passage 14 (pressure generation in the second direction Y) In the opposite side of the chamber 12, there is formed a communicating portion 15 which constitutes a part of the manifold 100 which becomes a common ink chamber of each pressure generating chamber 12. That is, in the flow path forming substrate 10, a liquid flow path including the pressure generating chamber 12, the ink supply path 13, the communication path 14, and the communication portion 15 is formed.

  The nozzle plate 20 is bonded to one surface of the flow path forming substrate 10 by an adhesive, a heat welding film, or the like. Nozzle openings 21 are formed in the nozzle plate 20 along the first direction X so as to communicate with the pressure generating chambers 12 respectively.

On the other side facing the one side of the flow path forming substrate 10, for example, an elastic film 51 made of silicon dioxide (SiO ₂ ) or the like, and an insulator film 52 made of zirconium oxide (ZrO ₂ ) or the like The diaphragm 50 is provided. However, the configuration of the diaphragm 50 is not limited to the above example, and part of the flow path forming substrate 10 may be processed to be thin. The materials of various configurations for forming the diaphragm 50 are not limited to the above examples.

  The insulator film 52 is provided with, for example, an adhesion layer (not shown) made of Ti or the like and having a thickness of about 10 to 50 μm, and the first electrode 60 having a thickness of about 0.2 μm is provided on the adhesion layer. Is provided. Then, a piezoelectric layer 70 having a thickness of about 3.0 μm or less, preferably about 0.5 to 1.5 μm, is provided so as to overlap the adhesive layer and the first electrode 60, and the piezoelectric layer 70 is further provided. A second electrode 80 having a thickness of about 0.05 μm is provided to overlap. Here, the piezoelectric element 300 refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80.

  In the piezoelectric element 300 of the present embodiment, a diffusion suppression layer 60 a for suppressing the diffusion of Mg is provided on the flow path forming substrate 10 side of the first electrode 60, and the piezoelectric layer is more than the diffusion suppression layer 60 a of the first electrode 60 On the side 70, a diffusion layer 60b for diffusing Mg compared to the diffusion suppression layer 60a is provided. The diffusion suppression layer 60 a and the diffusion layer 60 b are mainly composed of different materials, and the diffusion suppression layer 60 a has a function of suppressing the diffusion of the metal contained in the piezoelectric layer 70, and the diffusion layer 60 b is It has a function to diffuse the metal compared to the diffusion suppression layer 60a, and thus, in the present embodiment, the first electrode 60 is formed by stacking the diffusion suppression layer 60a and the diffusion layer 60b having mutually opposing functions. Is configured.

  The first electrode 60, the piezoelectric layer 70, and the second electrode 80 are not limited to those directly adjacent to each other, and other members may intervene within the scope of the present invention. For example, between the first electrode 60 and the piezoelectric layer 70, a metal layer (not shown) containing a metal such as Ti, an underlayer 73 made of PZT, and a composite oxide of another perovskite structure are used. The piezoelectric element 300 also includes one in which a seed layer (not shown) is disposed. Further, the insulator film 52 and the adhesion layer can be omitted, and the piezoelectric element 300 may be formed directly on the elastic film 51 by omitting these.

  Here, the piezoelectric element 300 and the element acting as a vibrating plate that is displaced by the drive of the piezoelectric element 300 are collectively referred to as an actuator. In the above example, the portion including the diaphragm 50 and the first electrode 60 can function as a diaphragm, but is not limited to this example, and any one or more of the elastic film 51, the insulator film 52 and the adhesion layer may be used. It may be made to act as a diaphragm without providing it, or only the first electrode 60 may be made to act as a diaphragm without providing all of them. Also, the piezoelectric element 300 itself may substantially serve as the diaphragm. However, when the first electrode 60 is provided directly on the flow path forming substrate 10, it is preferable to protect the first electrode 60 with an insulating protective film or the like so that the first electrode 60 and the ink do not conduct.

  In the piezoelectric element 300, generally, one of the electrodes is a common electrode, and the other electrode is an individual electrode by patterning for each pressure generation chamber 12. In the present embodiment, the second electrode 80 is a common electrode formed continuously over a plurality of pressure generation chambers 12 and the first electrode 60 is an individual electrode, but this may be for convenience of a drive circuit or the like. You may reverse the.

  Both ends of the first electrode 60 are extended to the outside of the pressure generation chamber 12 in the second direction Y of the first electrode 60. The end of the piezoelectric layer 70 on the ink supply path 13 side is located outside the end of the first electrode 60 in the second direction Y, and the side opposite to the ink supply path 13 (nozzle opening The end of 21) is located inside the end of the first electrode 60. That is, the end on the ink supply path 13 side of the first electrode 60 is covered by the piezoelectric layer 70, while the end on the nozzle opening 21 side is not covered by the piezoelectric layer 70.

  Recesses 71 corresponding to the respective partition walls 11 are formed in the piezoelectric layer 70. In the first direction X, the width of the recess 71 is substantially the same as or wider than the width between the partition walls 11. As a result, the rigidity of the portion (the so-called arm portion of the diaphragm 50) of the diaphragm 50 that opposes the end of the pressure generating chamber 12 in the second direction Y is suppressed, so that the piezoelectric element 300 can be favorably displaced. it can.

  The second electrode 80 is provided on the side of the piezoelectric layer 70 opposite to the first electrode 60. A lead electrode 90 is connected to the first electrode 60 and the second electrode 80 described above. Such a lead electrode 90 can be formed in a predetermined shape after being formed over the entire surface of the flow path forming substrate 10.

  An adhesive 35 bonds a protective substrate 30 for protecting the piezoelectric element 300 on the flow path forming substrate 10 in which the piezoelectric element 300 is formed. The protective substrate 30 is provided with a piezoelectric element holding portion 31 which is a concave portion which defines a space for housing the piezoelectric element 300, and a manifold portion 32 which constitutes a part of the manifold 100 is also provided. . The manifold portion 32 penetrates the protective substrate 30 in the thickness direction (the direction perpendicular to the first direction X and the second direction Y) and is formed across the width direction of the pressure generation chamber 12. As described above, the communication portion 15 communicates with the communication portion 15 of the flow path forming substrate 10.

  Apart from the above-mentioned manifold portion 32, the protective substrate 30 is provided with through holes 33 penetrating in the thickness direction so as to expose the lead electrodes 90 connected to the respective first electrodes 60. The protective substrate 30 is bonded to a compliance substrate 40 including a sealing film 41 and a fixing plate 42, and one surface of the manifold portion 32 is sealed by the sealing film 41. Further, a region of the fixing plate 42 facing the manifold 100 is an opening 43 completely removed in the thickness direction, and one surface of the manifold 100 is sealed only by the sealing film 41.

  In the ink jet recording head of this embodiment, after the ink is taken in from the ink introduction port connected to the external ink supply means (not shown) and the inside is filled with the ink from the manifold 100 to the nozzle opening 21, the drive is not shown. A voltage is applied between the first electrode 60 and the second electrode 80 corresponding to the pressure generating chamber 12 in accordance with the recording signal from the circuit, and the diaphragm 50, the adhesion layer, the first electrode 60, and the piezoelectric layer 70. Flex to deform. Thereby, the pressure in each pressure generation chamber 12 is increased, and the ink droplet is discharged from the nozzle opening 21.

  Here, with reference to FIG. 4 and FIG. 5 (a)-(c), the part regarding the actuator of this embodiment is further explained in full detail. FIG. 4 is an enlarged sectional view according to the line B-B 'of FIG. 3 (b) described above, and FIG. 5 is an enlarged view of a portion related to the first electrode 60 thereof.

  First, as shown in FIG. 4, the first electrode 60 is formed to have a width narrower than the width of the pressure generation chamber 12 in the first direction X. As described above, in the piezoelectric layer 70, the recess 71 which is substantially the same as or wider than the width between the partition walls 11 in the first direction X is formed. Here, the width is larger than the width between the partition walls 11 An example in which the width of the piezoelectric layer 70 is narrower than the width between the partition walls 11 is illustrated by the recess 71. The second electrode 80 is disposed so as to overlap the insulator film 52 in addition to the piezoelectric layer 70, but is not limited to the above example.

As described above, the piezoelectric element 300 constituting the actuator according to the present embodiment is a stack of the first electrode 60, the piezoelectric layer 70, and the second electrode 80. Among these, the piezoelectric layer 70 is made of a complex oxide of an ABO ₃ type perovskite structure containing Mg.

In the ABO ₃ -type perovskite structure, oxygen is coordinated to 12 at the A site, and oxygen is coordinated to 6 at the B site to form an octahedron (octahedron). In the complex oxide of the perovskite structure containing Mg, Mg is generally contained at the B site. Although a very small amount of Mg may be contained in the A site, the amount of Mg contained in the A site is a negligible amount with respect to the amount of Mg contained in the B site.

In this embodiment, a tetragonal crystal formed by solid solution of lead niobate (Pb (Mg _1/3 , Nb ′ _2/3 ) O ₃ ) and lead titanate (PbTiO ₃ ) as the piezoelectric layer 70. What consists of complex oxide represented with following General formula (1) (It may abbreviate as "PMN-PT" hereafter) containing ceramics is used. In the example of this composite oxide, Pb is located at the A site, and Mg, Nb and Ti are located at the B site.

When PMN-PT is used as the complex oxide of the perovskite structure containing Mg, use is made of the complex oxide represented by the following general formula (2) in which Pb is present in excess from the stoichiometry of the ABO ₃ structure. In addition, a part of Mg may be substituted by a metal species capable of having +2 valence such as Mn, Fe, Ni, Co, Zn, etc., and a part of Ti takes a +4 valence such as Zr. It may be substituted by the metal species. As a result, there is a possibility that the piezoelectric constant can be further improved. That is, within the scope of the present invention, as described above, those which deviate from the stoichiometric composition due to defects and excess, and those in which a part of the element is substituted by another element are also included in the present embodiment. It is included in the piezoelectric layer 70.

[Equation 1]
xPb (Mg _1/3 , Nb _2/3 ) O _3- (1-x) PbTiO ₃ (1)
x Pb _{1 + α} (Mg _1/3 , Nb _2/3 ) O _3- (1-x) Pb _{1 + α} TiO ₃
... (2)
(0.20 ≦ x ≦ 0.60 is preferable, 0.30 ≦ x ≦ 0.45 is more preferable)

  The above general formulas (1) and (2) are compositional notations based on stoichiometry, and as long as the perovskite structure can be taken within the scope of the present invention, the inevitable composition due to lattice mismatch or partial loss of elements etc. Deviations as well as partial substitution of unavoidable elements are, of course, permitted. For example, when the stoichiometric ratio is 1, those in the range of 0.85 to 1.20 are acceptable.

  The piezoelectric layer 70 made of the composite oxide represented by the general formulas (1) and (2) has a crystal structure which is tetragonal. Moreover, this crystal is {100} oriented on the flow path forming substrate 10. Furthermore, in the crystal lattice, regions having (100) planes and (001) planes perpendicular to the stacking direction are mixed. The stacking direction can be rephrased as the thickness direction of the piezoelectric element 300, and corresponds to a direction perpendicular to both the first direction X and the second direction Y described above.

  Since each region having (100) plane and (001) plane perpendicular to the stacking direction is mixed in the crystal lattice, the a-axis component and b-axis component of tetragonal crystal are c-axis component by application of an electric field. It is rotated by 90 °, which makes it possible to exhibit extremely excellent piezoelectric characteristics. In the present embodiment, in particular, the crystallite diameter of the piezoelectric material is an extremely small value (for example, 20 nm or less, and further 15 nm or less), and ferroelectricity is provided in each columnar grain disposed via the fired interface to constitute a thin film. Domains (so-called nanodomains) are formed. As a result, 90 ° domain rotation can be efficiently generated, and the piezoelectric characteristics can be further improved.

  Incidentally, a piezoelectric layer not accompanied by 90 ° domain rotation is also known apart from the piezoelectric layer 70 which generates displacement using such 90 ° domain rotation. However, since the piezoelectric layer is not displaced in an angular relationship such as 90 ° domain rotation, both are fundamentally different.

  A piezoelectric material that exhibits piezoelectric properties by induction of an electric dipole moment in a ferroelectric domain, unlike a piezoelectric material that uses 90 ° domain rotation, such as a complex oxide of a perovskite structure containing Mg In PZT), the composition ratio is often adjusted to realize a predetermined value by utilizing the property that the piezoelectric constant becomes extremely large near the morphotropic phase boundary where the crystal structure changes. On the other hand, the piezoelectric layer 70 made of a piezoelectric material utilizing 90.degree. Domain rotation as in the present embodiment can obtain displacement exceeding that of the above-described PZT in a range out of the composition ratio adjusted as such Has been confirmed.

As described above, by using PMN-PT containing Pb at the A site of the perovskite structure and Mg, Nb and Ti at the B site, the piezoelectric layer 70 can be further improved in piezoelectric characteristics. Can. However, the piezoelectric layer 70 is not limited to the above example. For example, Pb-magnesium leadate (Pb (Mg, Fe) O ₃ ) containing Pb at the A site of the perovskite structure, Mg and Fe at the B site, A Lead magnesium niobate (Pb (Mg, Nb) O ₃ ) containing Pb at site, Mg and Nb at site B, K, Na and Bi at site A, and magnesium niobate oxide with site Mg and Nb at site B Sodium potassium ((K, Na, Bi) (Mg, Nb) O ₃ ), Bi at the A site, bismuth titanate magnate containing Bi and Mg at the B site (Bi (Mg, Ti) O ₃ ), etc. May be

  That is, it further comprises at least one selected from the group consisting of Pb, Bi, K and Na at the A site, Mg at the B site of the perovskite structure, and at least one selected from the group consisting of Nb, Ti and Fe The piezoelectric layer 70 further includes the above-mentioned components, which is advantageous in improving the piezoelectric characteristics and ensuring high reliability. Also in these cases, within the scope of the present invention, those which deviate from the stoichiometric composition due to defects / excess, or some of the elements are substituted by other elements (such as Mn, Ni, Co, Zn, etc.) The resulting material is also included in the piezoelectric layer, and, of course, unavoidable compositional deviation due to lattice mismatch or partial loss of the element or the like, as well as partial substitution of the unavoidable element or the like is allowed.

  If possible, the piezoelectric layer may contain Mg at the A site of the perovskite structure. However, from the viewpoint of improving the piezoelectric characteristics and securing high reliability, the piezoelectric layer 70 containing Mg at the B site of the perovskite structure as described above is preferable.

  Such a piezoelectric layer 70 is stacked on the first electrode 60 via the underlayer 73 made of PZT. In particular, the base layer 73 has a lattice match of less than 1% with the c-axis of the complex oxide of the piezoelectric layer 70, and has a lattice mismatch of 1% or more with the a-axis and b-axis of the complex oxide. By forming such an underlayer 73, the orientation control of the piezoelectric material becomes easy, and the c-axis component of the tetragonal piezoelectric material can be stabilized. It is advantageous to improve. The total number of the base layers 73 is not limited, and the piezoelectric layers 70 and the base layers 73 may be alternately stacked.

 The first electrode 60 includes a diffusion suppression layer 60a and a diffusion layer 60b. The diffusion suppression layer 60a suppresses the diffusion of Mg. The diffusion layer 60 b diffuses the Mg as compared to the diffusion suppression layer 60 a. The diffusion suppression layer 60 a is provided closer to the flow path forming substrate 10 than the diffusion layer 60 b. The diffusion layer 60 b is provided closer to the piezoelectric layer 70 than the diffusion suppression layer 60 a.

  When a piezoelectric material composed of a complex oxide of a perovskite structure containing Mg is used, conventionally, depending on the material of the first electrode 60 and various aspects of the configuration, a firing process which is one of the processes of forming the piezoelectric layer In some cases, the Mg passes through the first electrode 60 and diffuses to the flow path forming substrate 10 and the diaphragm 50. In particular, shaping of a Si wafer by photolithography is often used for producing a MEMS element. Since Si reacts with the element of Mg to form magnesium silicate, when there is a heating step during the process of manufacturing the MEMS element, such a silicate is likely to be formed. If a silicate is formed, a good interface can not be formed. Therefore, for example, in the case of a liquid jet head, displacement characteristics and durability of the diaphragm may change, and problems such as deterioration of the discharge characteristics of ink or the like may occur. Also in the piezoelectric element used in applications other than the liquid jet head, there may be a problem of change in characteristics and deterioration for the same reason.

  However, in the present embodiment, the diffusion suppressing layer 60 a can prevent Mg from the piezoelectric layer 70 from passing through the first electrode 60 and reaching the flow path forming substrate 10 and the diaphragm 50. Then, Mg from the piezoelectric layer 70 can be diffused into the diffusion layer 60b by the above-mentioned diffusion layer 60b, and can be unevenly distributed in the first electrode 60, specifically, in front of the diffusion suppression layer 60a. Also, uneven distribution of Mg at the interface between the piezoelectric layer 70 and the first electrode 60 can be prevented. From the above, any of the piezoelectric layer 70 and the first electrode 60, and the first electrode 60 and the diaphragm 50 can form a favorable interface, and high reliability can be ensured.

  The diffusion suppression layer 60a can be made of, for example, a material containing Pt. By using a conductive noble metal material such as Pt, the diffusion of Mg from the piezoelectric layer 70 can be suitably suppressed.

The diffusion layer 60 b can be made of, for example, a material containing at least one selected from the group consisting of Ir, LaNiO ₃ and SrRuO ₃ . By using such a conductive material, it is possible to preferably diffuse Mg from the piezoelectric layer 70.

  However, the materials and structures of the diffusion suppression layer 60a and the diffusion layer 60b are not limited to the above examples. The diffusion suppression layer 60 a may be configured to have an Mg diffusion suppression function to such an extent that Mg from the piezoelectric layer 70 does not reach the flow path forming substrate 10 or the diaphragm 50. Further, the diffusion layer 60 b is configured to have a function to prevent Mg from the piezoelectric layer 70 from being localized at the interface with the first electrode 60 and to diffuse Mg compared to the diffusion suppression layer 60 a. It should just be. In the present embodiment, each layer is composed of a single layer, but may be composed of a plurality of layers. The diffusion suppressing layer 60a is disposed on the flow path forming substrate 10 side, and the diffusion layer 60b is disposed on the piezoelectric layer 70 side with respect to the diffusion suppressing layer 60a. The third diffusion suppression layer or the diffusion layer may be further disposed.

  The first electrode 60 of the present embodiment includes a Mg uneven distribution layer 60c in which Mg from the piezoelectric layer 70 is unevenly distributed on the diffusion suppression layer 60a side of the diffusion layer 60b. As shown in FIG. 5A, in the stage immediately after the preparation of the first electrode 60 (the stage in which the piezoelectric layer 70 is not prepared), the Mg uneven distribution layer 60c does not exist, and the diffusion suppressing layer 60a and the diffusion layer 60b Are adjacent to each other.

  When the formation of the piezoelectric layer 70 is started, Mg contained in the piezoelectric material is diffused to the first electrode 60 through the underlayer 73 made of PZT in the firing step included in the process of forming the piezoelectric layer 70. come. As shown in FIG. 5B, the Mg diffuses in the diffusion layer 60b of the first electrode 60, and a portion of the Mg tends to diffuse toward the diaphragm 50 side. However, the diffusion of Mg to the diaphragm 50 side is suppressed in front of the diffusion suppression layer 60a.

  The formation process of the piezoelectric layer 70 often includes a plurality of firing steps. When a plurality of firing steps are included, each time the firing step is performed, Mg contained in the piezoelectric material diffuses into the diffusion layer 60 b through the underlayer 73 made of PZT. The diffusion of Mg to the side is suppressed before the diffusion suppression layer 60a. Regardless of whether or not the number of firing steps is one or more, Mg whose diffusion is suppressed is likely to be retained in the portion on the diffusion suppression layer 60 a side of the diffusion layer 60 b. As a result, as shown in FIGS. 5B and 5C, the completed piezoelectric layer 70 has the Mg uneven distribution layer 60c in which Mg is unevenly distributed on the side of the diffusion suppression layer 60a of the diffusion layer 60b.

  The presence of such an Mg unevenly distributed layer 60c can be confirmed by performing measurement by secondary ion mass spectrometry in the direction from the piezoelectric layer 70 side to the flow path forming substrate 10 side. When measured by secondary ion mass spectrometry in the direction from the piezoelectric layer 70 side to the flow path forming substrate 10 side, the maximum strength of Mg in the Mg uneven distribution layer 60c is that of Mg in the diffusion suppression layer 60a and the diffusion layer 60b. Greater than strength. The presence of the Mg uneven distribution layer 60c is a proof that the diffusion suppressing effect of the diffusion suppressing layer 60a is high and the reliability of the piezoelectric element is high. That is, by having the Mg uneven distribution layer, high reliability can be ensured more reliably.

  The material of the second electrode 80 provided on the piezoelectric layer 70 is not particularly limited as long as the material has conductivity.

  Next, an example of the method of manufacturing the piezoelectric element of the present embodiment described above will be described together with an example of the method of manufacturing the ink jet recording head on which the piezoelectric element is mounted with reference to FIGS. .

  First, the diaphragm 50 is manufactured on the surface of the flow path forming substrate wafer 110 which is a silicon wafer. In this embodiment, silicon dioxide (elastic film 51) formed by thermally oxidizing the flow path forming substrate wafer 110, and zirconium oxide (insulator film 52) formed by thermal oxidation after film formation by a sputtering method. The diaphragm 50 which consists of lamination | stacking of and) was formed. As shown in FIG. 6A, in the present embodiment, an adhesion layer (not shown) made of Ti or the like is further formed on the diaphragm 50, but the adhesion layer can be omitted.

  Next, as shown in FIG. 6B, the diffusion suppression layer 60a and the diffusion layer 60b are sequentially formed on the entire surface of the adhesive layer of the diaphragm 50, thereby forming the first electrode 60. The diffusion suppression layer 60a and the diffusion layer 60b can be formed, for example, by vapor deposition such as sputtering, PVD (physical vapor deposition) or laser ablation, or liquid deposition such as spin coating. . As described above, at this stage (stage where the piezoelectric layer 70 is not formed), the diffusion suppression layer 60a and the diffusion layer 60b are in a state of being adjacent to each other.

  Next, the base layer 73 is formed on the first electrode 60. The method of forming the base layer 73 is not limited. For example, according to the MOD (Metal-Organic Decomposition) method, the base layer 73 made of a metal oxide can be obtained by applying and drying a solution containing a metal complex and baking it at a high temperature. The underlayer 73 can also be formed using a chemical solution method such as a sol-gel method. In addition, it can also be formed by a laser ablation method, a sputtering method, a pulse laser deposition method (PLD method), a CVD method, an aerosol deposition method or the like. Thus, the base layer 73 can be formed by various liquid phase methods or solid phase methods. The underlayer 73 can be omitted.

  Then, as shown in FIG. 6C, the first electrode 60 and the base layer 73 are simultaneously patterned. The patterning here can be performed by dry etching such as reactive ion etching (RIE) or ion milling, for example. The underlayer 73 may be formed after only the first electrode 60 is patterned. Alternatively, the first electrode 60 and the base layer 73 may be patterned together with the piezoelectric layer 70 after laminating the piezoelectric layer 70 described later on the base layer 73 without patterning the first electrode 60 and the base layer 73.

  Next, the piezoelectric layer 70 is formed. The method of forming the piezoelectric layer 70 is not limited. The piezoelectric layer 70 can be formed, for example, using a chemical solution method such as MOD method or sol-gel method, as in the example of the base layer 73. In addition to these methods, various liquid phase methods and solid phase methods can be used.

  The specific formation procedure example in the case of forming the piezoelectric material layer 70 by a chemical solution method is as follows. That is, a precursor solution for forming the piezoelectric layer 70 is made of a MOD solution or a sol containing a metal complex. Then, the precursor solution is applied to the first electrode 60 using a spin coating method or the like to form a precursor film 72 (application step). The precursor film is heated to a predetermined temperature and dried for a predetermined time (drying step), and the dried precursor film is heated to a predetermined temperature and held for a predetermined time to degrease (a degreasing step). The precursor film is crystallized by being heated to a predetermined temperature and held to form the piezoelectric layer 70 shown in FIG. 6D (baking step). In addition, in order to form the piezoelectric layer 70 having a sufficient thickness, the cycle from the coating process to the firing process may be repeated a plurality of times. In this case, in the process of forming the piezoelectric layer 70, the plurality of firing processes are performed. Will be included.

  As described above, in the firing step, Mg contained in the piezoelectric material diffuses through the underlayer 73 into the diffusion layer 60b of the first electrode 60, but the diffusion is suppressed before the diffusion suppression layer 60a. As a result, an Mg unevenly distributed layer 60c in which Mg is unevenly distributed is formed on the side of the diffusion suppression layer 60a of the diffusion layer 60b.

  The solution to be applied in the application step is a mixture of a metal complex capable of forming a precursor film of a complex oxide of a perovskite structure containing Mg by firing, and the mixture is dissolved or dispersed in an organic solvent. It is. Examples of the metal complex containing Mg include magnesium acetate and the like. Metal complexes containing other metals can also be used. For example, as a metal complex containing Pb, lead acetate and the like can be mentioned. Examples of metal complexes containing Bi include bismuth acetate and the like. Examples of the metal complex containing K include potassium acetate and the like. Examples of the metal complex containing Na include sodium acetate and the like. Examples of the metal complex containing Nb include niobium penta-n-butoxide and the like. Examples of metal complexes containing Ti include titanium tetra-i-propoxide. An iron acetate etc. are mentioned as a metal complex containing Fe.

  After the piezoelectric layer 70 is formed, as shown in FIG. 6E, the second electrode 80 made of Pt or the like is formed on the piezoelectric layer 70 by sputtering or the like to face each pressure generating chamber 12. The piezoelectric layer 70 and the second electrode 80 are simultaneously patterned in the region to form a piezoelectric element 300 including the first electrode 60, the piezoelectric layer 70, and the second electrode 80.

  Next, as shown in FIG. 7A, necessary portions such as the second electrode 80 are patterned to remove a portion thereof, and as shown in FIG. 7B, the lead electrode 90 is formed by sputtering or the like. Form The method of forming the lead electrode 90 is not limited to the sputtering method.

  Next, as shown in FIG. 8A, a protective substrate wafer 130, which is a silicon wafer and is to be a protective substrate 30, is bonded to the flow path forming substrate wafer 110 on the piezoelectric element 300 side with an adhesive 35 or the like. Thereafter, the flow path forming substrate wafer 110 is scraped and thinned to a predetermined thickness. Then, as shown in FIG. 8B, a mask film 54 is newly formed on the flow path forming substrate wafer 110, and is patterned into a predetermined shape. Further, as shown in FIG. 8C, the flow path forming substrate wafer 110 is subjected to anisotropic etching (wet etching) using an alkaline solution such as KOH via the mask film 54, to thereby form a piezoelectric element 300. The pressure generating chamber 12, the communication portion 15, the ink supply passage 13, the communication passage 14 and the like corresponding to the above are formed.

  Thereafter, unnecessary portions of the outer peripheral edge portions of the flow path forming substrate wafer 110 and the protective substrate wafer 130 are removed by, for example, dicing or the like. Then, after removing the mask film 54 on the surface of the flow path forming substrate wafer 110 opposite to the protective substrate wafer 130, the nozzle plate 20 (FIG. 3B) having the nozzle openings 21 formed therein is joined. Do. Further, by bonding the compliance substrate 40 (FIG. 3B) to the protective substrate wafer 130, the ink jet recording head 1 is completed.

  Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to the description of these Examples.

Example 1
Preparation of PZT Precursor Solution
A PZT precursor solution was prepared by measuring acetic acid and water, then measuring lead acetate, zirconium butoxide, and titanium tetra-i-propoxide and polyethylene glycol, and heating and stirring these at 90 ° C.

<Preparation of PMN-PT Precursor Solution>
2-butoxyethanol and dimethylaminoethanol were weighed to prepare a mixed solution. In a glove box filled with dry nitrogen, titanium tetra-i-propoxide and niobium penta-n-butoxide were weighed out and mixed with the above mixed solution. Thereafter, after sufficiently stirring at room temperature, magnesium acetate and lead acetate were weighed out respectively in the atmosphere, and mixed and stirred at room temperature to prepare a PMN-PT precursor solution.

<Production of First Electrode, Piezoelectric Layer, and Second Electrode>
By thermally oxidizing a 6-inch silicon substrate, a silicon dioxide film (elastic film 51) was formed on the substrate (flow path forming substrate 10). Next, a zirconium film was produced by sputtering and thermally oxidized to produce a zirconium oxide film (insulator film 52). By depositing titanium (Ti), platinum (Pt; diffusion suppressing layer 60a), iridium (Ir; diffusion layer 60b), and titanium (Ti) in this order on the insulator film 52 by sputtering, An electrode 60 was produced.

  The above PZT precursor solution was applied to the first electrode 60 by a spin coating method, and then drying / defatting was performed at 140 ° C. and 370 ° C. to produce a degreased film. The degreasing film was subjected to heat treatment at 737 ° C. in RTA (Rapid Thermal Annealing), whereby a ceramic film (base layer 73) made of PZT was produced.

  Next, the produced 1st electrode 60 and base layer 73 were patterned by dry etching, and the 1st electrode pattern was produced. The PMN-PT precursor solution described above was applied to the first electrode pattern by spin coating, and then drying / defatting was performed at 180 ° C. and 350 ° C. to produce a degreased film. The degreasing film was subjected to a heat treatment at 750 ° C. by RTA to produce a ceramic film (piezoelectric film 72) made of PMN-PT. By repeating the process of producing the ceramic film six times, a layer (piezoelectric layer 70) composed of a total of seven layers of the ceramic film was produced.

  After depositing a film of iridium and titanium in this order by sputtering on the produced piezoelectric layer 70, the electrode was baked at 740 ° C. by RTA. Thereafter, patterning is performed by dry etching, film formation is performed in the order of iridium and titanium by sputtering, and patterning is performed again by dry etching to fabricate a second electrode 80.

(Comparative example 1)
A piezoelectric element was produced in the same manner as in Example 1 except that the piezoelectric layer 70 was made of PZT.

<X-ray diffraction measurement using a two-dimensional detector>
For Example 1 and Comparative Example 1, “D8 Discover” manufactured by Bruker AXS, a radiation source is CuKα, and a detector is a two-dimensional detector (GADDS), and a two-dimensional mapping image and a diffraction pattern are measured The crystal structure and orientation of the piezoelectric layer were evaluated. The range that can be detected as an image is, from the limitation due to the device configuration, a typical ABO ₃ pseudo cubic (100) peak is detected 2θ = 22.5 ° equivalent φ = ± 30 °, the same (110) peak The detected 2θ = 32.5 ° corresponds to φ = ± 32 °, and the same (111) peak is detected 2θ = 40 ° corresponding to φ = ± 26 °. The X-ray-diffraction pattern in Example 1 (step before preparation of a 2nd electrode) is shown in FIG.

As illustrated, in Example 1, only peaks of Si, ZrO ₂ , Pt, PZT, and PMN-PT were observed, and no hetero phase was observed. The crystal structure of the piezoelectric layer 70 in Example 1 is that (100) and (001) and (200) and (002) are clearly separated (although the peak is overlapped with the PZT, PMN- From the fact that (001) and (002) of PT can be confirmed), it can be seen that the tetragonal crystal structure is still in consideration of the general PMN-PT phase diagram.

  Regarding the orientation of such crystal structure, it is observed that only the peaks of (100) and (001) are observed in FIG. 9 and that the {100} orientation is 99% or more based on the two-dimensional photograph. It became clear.

  As a result of performing the same measurement also about comparative example 1, it is a pseudo cubic and a hetero phase is not observed. Although detailed description is omitted, it seems that it is likely to be trigonal from other measurements and literatures, but it could not be identified by X-ray diffraction measurement here.

<Displacement characteristics measurement using DBLI>
The piezoelectric characteristics (displacement characteristics) of the piezoelectric element were evaluated for Example 1 and Comparative Example 1 by using aix ACCT Double-Beam Laser Interferometry (DBLI). The results are shown in FIG. As shown, in the piezoelectric element of Example 1 represented by the solid line, the maximum displacement (maximum strain-minimum strain: D _pp2 ) was 7.1 nm, while Comparative Example 1 represented by the dotted line Then, it was D _pp2 = 3.6 nm. From this, it became clear that the piezoelectric element of Example 1 is superior to the piezoelectric element of Comparative Example 1 in displacement characteristics and exhibits a displacement of 1.95 times.

<Secondary ion mass spectrometry>
Regarding Example 1 and Comparative Example 1, secondary ion mass spectrometry was performed from the piezoelectric layer 70 in the thickness direction using “ADEPT-1010” manufactured by ULVAC-PHI, Inc. to evaluate the distribution state of Mg. . The result in Example 1 is shown in FIG. 11, and the result in Comparative Example 1 is shown in FIG. In each figure, the vertical axis is the detection intensity normalized by ¹⁶ O + ¹³³ Cs, and the horizontal axis is the sputtering time. Since the passage of sputtering time corresponds to the depth in the thickness direction, in FIGS. 11 and 12, the state of Mg at a deep point from the piezoelectric layer 70 toward the diaphragm 50 is evaluated as the horizontal axis advances to the right. It will be done.

First, in Comparative Example 1 shown in FIG. 12, the peak of ²⁴ Mg + ¹⁶ O was not observed. From this, it can be seen that ²⁴ Mg + ¹⁶ O can be measured in PZT, Ir, Pt and ZrO ₂ without being affected by interference elements under the present measurement conditions.

On the other hand, in Example 1 shown in FIG. 11, the peak of ²⁴ Mg + ¹⁶ O is in the range of the piezoelectric layer 70 made of PMN-PT, and the Pt layer (diffusion suppression layer 60 a) in the Ir layer (diffusion layer 60 b). The range in front of) was observed. On the other hand, in the range of the base layer 73 made of PZT, Mg diffused from PMN-PT is slightly observed, and in the lower ZrO ₂ layer (insulator film 52) of the diffusion suppression layer 60a, a superior amount of Mg is observed It was not done. From this, Mg diffuses and passes through the underlayer 73 made of PZT at the time of firing, and passes through the Ir layer (the diffusion layer 60b) having a high Mg permeability, a Pt layer having a low Mg diffusibility (diffusion suppression Diffusion is suppressed in front of the layer 60a), and as a result, Mg becomes unevenly distributed in front of the diffusion suppression layer 60a in the diffusion layer 60b (Mg uneven distribution layer 60c), and the diffusion of Mg to the diaphragm 50 is It turned out that it was suppressed.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, the basic composition of this invention is not limited to what was mentioned above. For example, although a silicon single crystal substrate is illustrated as the flow path forming substrate 10 in the above embodiment, the invention is not particularly limited thereto. For example, a material such as an SOI substrate or glass may be used.

  An example of a piezoelectric element application device other than the ink jet recording head using the piezoelectric element of the present invention in the electromechanical conversion mechanism of the MEMS element will be described. For example, as a piezoelectric element application device, a control unit that measures a detection target using a signal based on at least one of the piezoelectric element of the present invention, an ultrasonic wave transmitted by the piezoelectric element, and an ultrasonic wave received by the piezoelectric element The ultrasonic measurement apparatus can also be configured by including.

  Such an ultrasonic measurement device is based on the time from when an ultrasonic wave is transmitted to when the transmitted ultrasonic wave is reflected by the object to be received and an echo signal is returned. It obtains information on the position, shape, velocity, etc., and may use an element for generating an ultrasonic wave or a piezoelectric element as an element for detecting an echo signal. If the piezoelectric element of the present invention in which the piezoelectric constant is improved is used as such an ultrasonic wave generation element or an echo signal detection element, an ultrasonic measurement device having an enhanced ultrasonic wave generation efficiency and an echo signal inspection efficiency is obtained. Can be provided.

  In addition, as a piezoelectric element applied device, it is of course possible to configure a liquid jet head which jets liquid other than ink. As such a liquid jet head, for example, various recording heads used in an image recording apparatus such as a printer, a color material jet head used in the manufacture of a color filter such as a liquid crystal display, an organic EL display, an FED (field emission display) And the like, and an organic material jet head used for producing a biochip and the like.

  In addition, as piezoelectric element application devices, for example, ultrasonic devices such as ultrasonic transmitters, ultrasonic motors, temperature-electric transducers, pressure-electric transducers, ferroelectric transistors, piezoelectric transformers, harmful rays such as infrared rays Filters, optical filters using the photonic crystal effect by quantum dot formation, and filters such as optical filters using light interference of thin films. Further, the piezoelectric element of the present invention can be applied to a piezoelectric element used as a sensor and a piezoelectric element used as a ferroelectric memory, whereby a piezoelectric element applied device can be configured. Examples of the sensor in which the piezoelectric element is used include an infrared sensor, an ultrasonic sensor, a thermal sensor, a pressure sensor, a pyroelectric sensor, and a gyro sensor (angular velocity sensor).

  In addition, as a piezoelectric element application device, one using the piezoelectric element 300 of the present invention as a ferroelectric element is included. As a ferroelectric element that can be suitably used, a ferroelectric transistor (FeFET), a ferroelectric arithmetic circuit (FeLogic), a ferroelectric capacitor and the like can be mentioned. Furthermore, since the piezoelectric element 300 of the present embodiment exhibits good pyroelectric characteristics, it can be suitably used for a pyroelectric element. As a pyroelectric element which can be suitably used, a temperature detector, a living body detector, an infrared detector, a terahertz detector, a thermal-electrical converter and the like can be mentioned.

  I ink jet recording head (liquid jet head), II ink jet recording apparatus (liquid jet device), 10 flow path forming substrate, 12 pressure generating chamber, 13 ink supply path, 14 communicating path, 15 communicating portion, 20 nozzle plate, 21 nozzle opening, 30 protective substrate, 31 piezoelectric element holding portion, 32 manifold portion, 33 through hole, 35 adhesive, 40 compliance substrate, 41 sealing film, 42 fixing plate, 43 opening portion, 50 diaphragm, 51 elastic film , 52 insulator film, 54 mask film, 60 first electrode, 60a diffusion suppression layer, 60b diffusion layer, 60c Mg uneven distribution layer, 70 piezoelectric layer, 71 recess, 72 piezoelectric film, 80 second electrode, 90 lead electrode , 100 manifolds, 300 piezoelectric elements,

Claims (6)

A piezoelectric element in which a first electrode, a piezoelectric layer made of a composite oxide of an ABO ₃ -type perovskite structure containing Mg, and a second electrode are stacked from the substrate side,
The first electrode includes a diffusion suppression layer which suppresses the diffusion of the Mg, and a diffusion layer containing Ir, which diffuses the Mg relative to the diffusion suppression layer,
The diffusion suppression layer is provided closer to the substrate than the diffusion layer ,
A piezoelectric element comprising an Mg uneven distribution layer in which the Mg is unevenly distributed on the diffusion suppression layer side of the diffusion layer . When the strength of the Mg is measured by secondary ion mass spectrometry in the direction from the piezoelectric layer side to the substrate side, the maximum strength of Mg in the Mg uneven distribution layer is the Mg of the diffusion layer and the diffusion suppression layer The piezoelectric element according to claim 1, wherein the strength of the piezoelectric element is greater than that of the piezoelectric element. The piezoelectric layer is
And at least one selected from the group consisting of Pb, Bi, K and Na at the A site of the ABO ₃ type perovskite structure,
The piezoelectric element according to claim 1 or 2 , wherein the B site of the ABO ₃ type perovskite structure further includes at least one selected from the group consisting of Nb, Ti, and Fe, which contains the Mg. The piezoelectric element according to any one of claims 1 to 3 , wherein the diffusion suppression layer contains Pt. A piezoelectric element application device comprising the piezoelectric element according to any one of claims 1 to 4 . A method of manufacturing a piezoelectric element, comprising laminating a first electrode, a piezoelectric layer made of a complex oxide of ABO ₃ -type perovskite structure containing Mg, and a second electrode from the substrate side,
In the step of forming the first electrode,
Providing a diffusion suppression layer for suppressing the diffusion of the Mg;
The diffusion suppressing layer, the compared to the diffusion suppressing layer to diffuse the Mg, only set a diffusion layer containing Ir, the diffusion suppressing layer side of the diffusion layer, setting the Mg uneven distribution layer in which the Mg is unevenly distributed And manufacturing the piezoelectric element.

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